In recent years, in order to improve environment performance of an automobile such as fuel economy, development and launching of a vehicle that uses electric power instead of a conventional internal combustion engine like an electric vehicle, a hybrid vehicle, or a fuel cell vehicle have rapidly been promoted. A power conversion equipment that converts the electric power to motive power is mounted on such an automobile. In addition, in order to achieve a high output characteristic and a high efficiency package, a water cooling method using an engine coolant has been a predominant method of cooing a heat generation element in the power conversion equipment. With this water cooling characteristic, an anti-vibration property, a waterproof property, salt water resistance, and dust resistance have been requested for a casing of the power conversion equipment that is mounted in an engine room.
Furthermore, in order to achieve high functionality, components such as a water-cooled heat sink that cools the heat generation element like a switching element, a control circuit substrate, and a booster converter are accommodated in the casing of the power conversion equipment. Moreover, a smoothing capacitor that suppresses a ripple current, a terminal block for electric power connection, a terminal block for motor connection, and the like are accommodated in the casing of the power conversion equipment. Then, those components are electrically joined by a harness and a bus bar of a high-pressure system and a low-pressure system.
In the power conversion equipment on which a large number of the components as described above are mounted, in order to reduce size, weight, and cost and improve the antivibration property and assemblability, each of the components, such as the control circuit substrate, is attached to the casing that also serves as a structural material. After portions of the casing, to each of which the components are attached, are fastened, the casing is electrically joined by using a service hole thereof, and the service hole is lastly sealed by a rubber plug (for example, see PTL 1).